Liquid cooled frictional mechanism



Nov. 7, 1961 .1. o. EAMES LIQUID-COOLED FRICTIONAL MECHANISM 2 Sheets-Sheet 1 Filed Jan. 2, 1959 FIG. 3

INVENTOR JAMES Owen EAMES ATTORNEY Nov. 7, 1961 .1. o. EAMES LIQUID-COOLED FRICTIONAL MECHANISM 2 Sheets-Sheet 2 Filed Jan. 2. 1959 FIG. 2

ATTORNEY 3,007,556 LIQUll) COOLED FRICTIONAL MECHANISM James Owen Eames, Washington, Conn. (P.0. Box 400, Seymour, Comm), assignor to Roy S. Sanford, Wilfred A. Eaton, and Erling l). Sedergren, all of Woodbury, Conn, and Roger H. Casler and James 0. Earnes, both of Washington, Conn.

Filed Jan. 2, 1959, Ser. No. 784,665 7 Claims. (Cl. 188264) This invention relates to frictional mechanisms, and more particularly to frictional mechanisms of the liquid cooled type adapted for use, for example, as brakes or clutches.

The heat developed in frictional mechanisms of this type has caused great difliculties in the past, and it is accordingly one of the objects of the invention to provide means for overcoming these difliculties.

Another object of the invention is the provision of novel cooling means for a frictional mechanism.

Yet another object of the invention is the provision, in a frictional mechanism of the above type, of liquid cooling means which is self-contained.

A further object of the invention is to provide frictional mechanisms of the above type, wherein a cooling liquid is automatically circulated in the mechanism.

A still further object of the invention is the provision of means for controlling the pressure of the cooling liquid in the mechanism.

Another object of the invention is the provision of means for cooling the liquid in the brake mechanism.

These and other objects of the invention will be more readily apparent from the following detailed description when taken in connection with the accompanying drawings. It is to be expressly understood, however, that the description and drawings are not to be taken as defining the limits of the invention, reference being had for this purpose to the appended claims.

In the drawings, wherein similar reference characters. are utilized throughout the several views, FIG. 1 is a side elevation view in section of a frictional mechanism constructed in accordance with the principles of the invention;

FIG. 2 is an end view of the mechanism of FIG. 1, partially broken away and taken from the right, and

PEG. 3 is a fragmentary sectional view of a portion of the mechanism shown in FIG. 2.

Although the matter of liquid cooling for frictional mechanisms has received considerable attention in the past, many of the mechanisms proposed have involved considerable outside piping and. rotary seals, and have also required the use of a circulating pump of some sort to circulate the cooling liquid through the mechanism. It has been found that in many cases, however, adequate cooling may be provided by using a properly constructed mechanism having a chamber for cooling liquid which is substantially selfcontained, and with provision being made for a thermo-syphon circulation of the cooling liquid in order to transmit heat to the entire body of cooling liquid in the mechanism and thence to the surrounding atmosphere. Such mechanisms are particularly adaptable to industrial and other uses, wherein a brake or clutch is operated periodically, with a rest period between engagements which allows dissipation of the heat from the cooling liquid and from the metal of the mechanism to the surrounding atmosphere. Although the construction set forth in the present application is particularly adapted to installation as a drive shaft brake on a vehicle or as a clutch on an industrial machine, it will be understood by those skilled in the art that the invention is also adapted to other applications without limitation as to the exact configuration or arrangement of the mecha- Tnited States Patent ice nism. The invention is particularly adapted to, but not limited to, brakes or clutches of the external contracting type, wherein a drum having an external cylindrical friction surface is engaged by a brake band or brake shoes which are moved radially inward into frictional engagement with the external friction surface of the drum.

In its broad aspects, the invention contemplates a hollow drum member having a cooling liquid therein adapted to be circulated by thermo-syphon action, together with a brake band or shoe adapted to engage a friction surface formed on a portion of the drum member. Although the brake drum member may be preferably constructed in such a manner as to include a separate metallic friction element engageable by the brake shoe and formed of a metal particularly adapted for the intended service, it will be understood that the metallic friction element above referred to may be formed, if desired, as an integral part of the drum member structure without departing in any way from the spirit of the invention. In the event a separate friction element is utilized, however, it has been found that substantially pure copper or silver and some of the high conductivity alloys thereof are extremely satisfactory for such service, as they not only have exceptional wear characteristics when utilized in connection with the proper type of low heat conductivity composition lining, commonly known as brake lining, but also serve to conduct heat rapidly from the friction surface to the cooling liquid in order to prevent over heating of the drum member friction surface and the adjacent brake lining.

Referring more particularly to FIG. 1 of the drawings,

the mechanism includes a drum member 4 mounted on a shaft 5 and connected thereto as by means of suitable key 6. The brake drum member includes an inner annular cooling liquid chamber 7, and an outer annular cooling liquid chamber 8, the latter chamber being spaced radially outward as shown from the inner chamber 7. A cylindrical supporting surface 9 is formed on the brake drum member as shown, and at the right hand portion of the member, a cylindrical bore 10 is formed. A cup-shaped metal friction element 11 is provided, preferably formed of copper or silver or some of the high conductivity alloys thereof, this element having a cylindrical portion 12 having its outer periphery in sliding engagement with the bore 10 at the right end of the element, while at the left end of the element, a flange 13 formed on the element is secured to the left end of the drum member as by means of crap screws 14, leakage of cooling liquid at the left end of the element being prevented by means of a resilient sealing ring 15, and at the right end by means of a resilient sealing ring 16. The inner surface of the element 11 is formed in the same manner as an internal gear, being provided with a plurality of substantially V-shaped teeth 17, the peaks of these teeth being in supporting engagement with the cylindrical surface 9 formed on the drum member. Thus it will be seen that valleys 18 between the teeth form axially extending passages for cooling liquid substantially coextensive with the cylindrical portion of the metal friction element. These passages are connected at their right ends as shown With the outer cooling liquid chamber 8, and at their left ends are connected by a passage or passages 19 with the inner cooling liquid chamber 7.

In order to provide for a thermo-syphon circulation of the cooling liquid, as well as to provide for efficiently cooling this liquid during such circulation, a tubular heat exchanger 20 is secured to the right end of the drum member, this tubular heat exchanger in the embodiment shown being in the form of a tube 20a Wound in a fiat spiral. The heat exchanger has an inner connecting mem ber 21 and an outer connecting member 22, these connecting members being positioned respectively at the Patented Nov. 7, i961.

radially inner and outer ends of the spiral tubing. The member 21 is connected as shown to the inner cooling liquid chamber through an outlet port 22a, while the connecting member 22 is connected to the outer cooling liquid chamber through an inlet port 23. It will be noted that the port 22a is located in a position adjacent the central portion of the drum, while the port 23 is positioned adjacent the outermost portion of the drum member and radially outward from the valleys 18 between the teeth 17 on the metal friction element 11, the port 23 being connected through a passage 24 with the outer cooling liquid chamber. Although a particular arrangement of connecting passage is shown between the connecting member 22 and the outer cooling liquid chamber 8, it will be understood that the member can otherwise be connected provided the connection is made at a region in the outer portion of the outer cooling liquid chamber 8. The chambers may be filled with cooling liquid through a filler plug 25, shown in FIG. 2, and sufficient liquid should be provided in the drum member so that when the member is rotating at any appreciable speed, the liquid assumes a level substantially along the line shown at 26. In any case the port 22a should be covered at all times, this being essential to the proper thermo-syphcn circulation of the liquid. In order to relieve excess pressure from the chambers when the mechanism is operating, an outlet port 27 is provided in the wall of the inner chamber 7', and this port is spaced radially inward from the innermost portion of the port 22. This outlet port is normally closed by means of a ball valve 28 maintained against the outer end of the port by means of a spring 29, this spring being held in place by means of a screw plug 30 as shown. An exhaust port 31 is provided, and it will be understood that when the pressure in the inner chamber 7 reaches a predetermined value determined by the tension of the spring 29, the valve will open and vapor or steam will be discharged to atmosphere through the port 27 and the port 31. It should also be noted, that when the drum member is rotating, the port 27 is so positioned'with relation to the liquid level in the inner chamber, that liquid will not be discharged by the relief valve to atmosphere.

In order to provide for more efficient cooling of the liquid passing through the spiral tube 20a, the tube is provided as shown in FIGS. 1 and 2 with closely spaced rectangular cooling fins 32, these fins being normal to the tube wall and thus lying substantially in radial planes passing through or adjacent the axis of rotation of the. drum member. Thus these fins serve as the blades of a centrifugal blower as shown more particularly in FIG. 2. In order to further enhance the effect of these fins as the blades of a blower, an annular plate 33 is secured to the drum member by means of cap screws 34, the plate being spaced from the right end of the drum member by bosses 35 to which the cap screws are attached. A central bore 36 is provided in the plate, and the outer periphery 37 of the plate is of substantially the same diameter as the outer periphery of the right hand portion of the drum member 4. Thus, when the drum member is rotating, air is drawn in through the bore 36, passes radially outward between the fins 32, and is discharged through opening 38 at the periphery of the plate and drum member, thus providing very efiicient air cooling of the fins and of the tube 20a on which the fins are mounted.

Referring now to the thermo-syphon circulation of the cooling liquid which results from this novel arrangement, it will be noted that when the drum member is rotating, the pressure of liquid in the outer chamber 8, due to centrifugal force acting on the liquid, is appreciably greater than the pressure in the inner cooling liquid chamber 7. As shown in FIG. 1, a brake band 39 is provided having brake lining 40 on its inner surface, and on contraction of the brake band by suitable means, not shown, the lining engages the outer surface of the element 11, tending to retard the rotation thereof and causing the generation of heat at the interface between the lining-and the friction element. This heat is imparted to the liquid in the valleys or passages 18 between the internal teeth on the friction element, and as the liquid is heated, it becomes lighter and tends to fiow toward a region of lower pressure, which in this case is the inner cooling liquid chamber 7. The pressure in the outer chamber, and particularly at the port 23, is, due to centrifugal force, appreciably greater than that in the passage H at the left end of the internal teeth 17. Consequently a thermosyphon flow of liquid is set up through the passage or passages 19 in to the inner cooling liquid chamber 7, and as this liquid is cooled, it again becomes heavier and is thrown outward by centrifugal force through the port 22a and the spiral tube 20a, thus supplying cooled liquid to the outer cooling liquid chamber through the port 23 and the passage 24. It will thus be apparent that the liquid must circulate in this direction, and that the direction of flow is positively controlled during operation of the mechanism. The cooling action of the heat exchanger, due to the efficient blower action obtained and to the large cooling surface exposed to the air passing through the heat exchanger, is very efiicient, and the rotation of the drum member and heat exchanger is thus utilized to insure this efiicient cooling action.

Although a particular configuration of heat exchanger has been shown, it will be understood that the heat exchanger tube and' fins may take other forms as will be readily understood by those skilled in the art, it being important, however, that one end of the heat exchanger tube or tubing be connected to the inner chamber, and that the other end be connected to an outer chamber spaced radially outward from the inner chamber. It will also be understood that if desired the teeth on the inner surface of the friction element 11 may be omitted and that the element may be supported by other suitable means. In any case, however, substantially the entire inner surface of the metal friction element is subjected to the action of the cooling liquid which passes along the inner surface thereof from the outer chamber to the inner chamber and thence back to the outer chamber through the tubing of the heat exchanger. It is also to be understood that the mechanism shown may be utilized as either a clutch or a brake, depending upon the arrangement of the mechanism.

Although the invention has been illustrated and described herein with considerable particularity, it is to be understood that the invention is not to be considered as limited thereto, but may be embodied in other forms as may well suggest itself to those skilled in the art. Reference will, therefore, be had to the appended claims for a definition of the limits of the invention.

What is claimed is:

1. Liquid cooled frictional mechanism including a rotatable drum member having an annular inner chamber for cooling liquid, said inner chamber having an outlet port, an annular outer chamber for cooling liquid spaced radially outward from said inner chamber and having an inlet port, a wall on said member having a radially outer surface adapted to be engaged by a brake shoe and an opposite radially inner surface portion adapted to be engaged by a cooling liquid, means for conducting cooling liquid along said inner surface portion including a passage extending along said inner surface portion, means for connecting said conducting means at one end thereof with said inner chamber, means for connecting said conducting means at the other end thereof with said outer chamber, and a tubular heat exchanger mounted on the outside of the drum member for rotation therewith, said heat exchanger being connected at one end thereof with said inlet port, and being connected at the other end thereof to said outlet port, said chambers, ports, conducting means, connecting means and heat exchanger constituting a continuous closed circuit for the circulation of cooling liquid.

.2. Liquid cooled frictional mechanism as set forth in claim 1, wherein said heat exchanger is a tube spirally Wound substantially in a plane perpendicular to the axis of rotation of the drum member, the outer end of the tubing being connected to said inlet port and the inner end being connected to said outlet port.

3. Liquid cooled frictional mechanism as set forth in claim 1, wherein said heat exchanger is a tube spirally wound substantially in a plane perpendicular to the axis of rotation of the drum member, one end of the tube is connected to said inlet port and the other end is connected to said outlet port, and the tube is provided with a plurality of cooling fins, said fins being generally radial with respect to the axis of rotation of the drum and forming the blades of a centrifugal blower.

4. Liquid cooled frictional mechanism as set forth in claim 1, wherein said inner chamber is provided with an exhaust port spaced radially inward from said inlet port, and a relief valve is connected to said exhaust port, said valve being set to relieve the pressure of said inner chamber when said pressure exceeds a predetermined value.

5. Liquid-cooled frictional mechanism including a rotatable drum member having an annular inner chamber for cooling liquid, said inner chamber having an outlet port, an annular outer chamber for cooling liquid spaced radially outward from said inner chamber and having an inlet port, a Wall on said member having an outer surface adapted to be engaged by a brake shoe and an opposite inner surface portion adapted to be engaged by a cooling liquid, means for conducting cooling liquid along said inner surface portion including a passage extending along said inner surface portion, means for connecting said conducting means at one end thereof with said inner chamber, means for connecting said conducting means at the other end thereof with said outer chamber, a tubular heat exchanger mounted on the out-side of the drum member for rotation therewith having one end connected to said inlet port and the other end connected to said outlet port, the tube of said exchanger being spirally wound substantially in a plane perpendicular to the axis of rotation of the drum member and being provided with cooling fins positioned generally radial with respect to the axis of rotation of the drum member and forming the blades of a centrifugal blower, and an annular plate enclosing said fins and tube, said plate having a central opening for the admission of cooling air and having its outer periphery spaced radially outward from said bore and forming, in connection with said drum member, an outlet for cooling air at the periphery of the drum member and plate.

6. Liquid-cooled frictional mechanism including a rotatable drum member having an annular inner chamber for cooling liquid, said inner chamber having an outlet port, an annular outer chamber for cooling liquid spaced radially outward from said inner chamber and having an inlet port, a wall on said member having an outer surface adapted to be engaged by a brake shoe and an opposite inner surface portion adapted to be engaged by a cooling liquid, means for conducting cooling liquid along said inner surface portion including a passage extending along said inner surface portion, means for connecting said conducting means at one end thereof with said inner chamber, means for connecting said conducting means at the other end thereof with said outer chamber, a tubular heat exchanger mounted on the outside of the drum member for rotation therewith having one end connected to said inlet port and the other end connected to said outlet port, the tube of said heat exchanger being spirally wound substantial ly in a plane perpendicular to the axis of rotation of the drum member and being provided with a plurality of substantially rectangular cooling fins positioned generally radial with respect to the axis of rotation of the dirum member with their inner edges abutting an end wall of the drum member, and an annular plate secured to the drum member with its inner surface abutting the outer edges of said fins, said plate having a central bore for the admission of cooling air and having its outer periphery spaced radially outward from said bore and forming, in connection with the drum member, an outlet for cooling air at the periphery of the drum member and plate.

7. Liquid cooled frictional mechanism including a rotatable drum member having an annular inner chamber for cooling liquid, said inner chamber having an outlet port, an annular outer chamber for cooling liquid spaced radially outward from said inner chamber and having an inlet port, a wall on said member having an outer surface adapted to be engaged by a brake shoe and an opposite inner surface portion adapted to be engaged by a cooling liquid, means for conducting cooling liquid along said inner surface portion including a passage extending along said inner surface portion, means for connecting said conducting means at one end thereof with said inner chamber, means for connecting said conducting means at the other end thereof with said outer chamber, and a tubular heat exchanger mounted on the outside of the drum member for rotation therewith, said heat exchanger being connected at one end thereof with said inlet port, and being connected at the other end thereof with said outlet port, said outer surface being an external cylindrical surface adapted to be engaged by a brake shoe on movement of the latter radially inward and said external surface being positioned radially inward from said inlet port.

References Cited in the file of this patent UNITED STATES PATENTS 1,038,092 Craig Sept. 10, 1912 1,049,677 Craig Jan. 7, 1913 1,697,825 Williams et a1 Jan. 1, 1929 1,832,686 Bloss Nov. '17, 1931 1,894,001 Myers Jan. 10, 1933 2,041,457 Cautley May 19, 1936 2,317,528 Hertrich Apr. 27, 1943 2,724,953 Justice Nov. 29, 1955 2,940,549 Hause et al. June 14, 1960 FOREIGN PATENTS 357,726 France Nov. 22, 1905 438,171 France Mar. 8, 1912 1,017,181 France Sept. 17, 1952 

